Long preamble and duty cycle based coexistence mechanism for power line communication (PLC) networks

Abstract

Embodiments of methods and systems for supporting coexistence of multiple technologies in a Power Line Communication (PLC) network are disclosed. A long coexistence preamble sequence may be transmitted by a device that has been forced to back off the PLC channel multiple times. The long coexistence sequence provides a way for the device to request channel access from devices on the channel using other technology. The device may transmit a data packet after transmitting the long coexistence preamble sequence. A network duty cycle time may also be defined as a maximum allowed duration for nodes of the same network to access the channel. When the network duty cycle time occurs, all nodes will back off the channel for a duty cycle extended inter frame space before transmitting again. The long coexistence preamble sequence and the network duty cycle time may be used together.

What is claimed is: 
     
       1. A method comprising:
 performing, by a power line communication (PLC) device,
 detecting a coexistence preamble sequence followed by not detecting a native preamble from a remote PLC device on a channel in a PLC network, wherein the coexistence preamble sequence comprises m repeated coexistence preambles so that the coexistence preamble sequence has a duration longer than a largest packet size of different PLC technologies operating on the PLC network; 
 determining whether a threshold back-off duration has been reached; and 
 transmitting the coexistence preamble sequence in response to a determination that the threshold back-off duration has been reached. 
 
 
     
     
       2. The method of  claim 1 , further comprising:
 transmitting a data frame on the channel after transmitting the coexistence preamble sequence. 
 
     
     
       3. The method of  claim 1 , wherein a size of the coexistence preamble sequence is selected based upon a maximum packet size for the PLC device. 
     
     
       4. The method of  claim 1 , wherein the threshold back-off duration is defined as a predetermined number N of coexistence Extended Interframe Space (cEIFS) durations for the PLC network. 
     
     
       5. The method of  claim 1 , further comprising:
 determining that a first coexistence preamble sequence has been transmitted on the channel; and 
 delaying transmission of a second coexistence preamble sequence on the channel for at least a threshold back-off duration. 
 
     
     
       6. A method comprising:
 performing, by a power line communication (PLC) device,
 monitoring a channel occupancy duration during which devices transmit on a channel in a PLC network; 
 determining when the channel occupancy duration of a given PLC technology exceeds a network duty cycle time (ndcTime); 
 backing off from the channel for a duty cycle Extended Interframe Space (dcEIFS) duration when the channel occupancy duration exceeds ndcTime, wherein values for the ndcTime and dcEIFS parameters are selected based upon channel access technologies used by PLC devices on the PLC network; 
 detecting a coexistence preamble sequence from a remote PLC device on the PLC network channel; 
 determining whether a threshold back-off duration has been reached; and 
 transmitting the coexistence preamble sequence in response to a determination that the threshold back-off duration has been reached. 
 
 
     
     
       7. The method of  claim 6 , further comprising:
 transmitting a data frame on the channel after transmitting the coexistence preamble sequence. 
 
     
     
       8. The method of  claim 6 , wherein the coexistence preamble sequence comprises two or more repeated coexistence preambles. 
     
     
       9. The method of  claim 6 , wherein the threshold back-off duration is defined as a predetermined number N of coexistence Extended Interframe Spaces (cEIFS) durations for the PLC network. 
     
     
       10. The method of  claim 9 , wherein the values of ndcTime and N are selected so that ndcTime is less than the value of (N×cEIFS). 
     
     
       11. A power line communication (PLC) device, comprising:
 a receiver coupled to a channel on a PLC network; 
 a processor; and 
 a memory coupled to the processor, the memory configured to store program instructions executable by the processor to cause the PLC device to:
 detect a coexistence preamble sequence followed by not detecting a native preamble from a remote PLC device on the PLC network channel, wherein the coexistence preamble sequence comprises m repeated coexistence preambles so that the coexistence preamble has a duration larger than the largest packet size of the different PLC technologies; 
 determine whether a threshold back-off duration has been reached; and 
 transmitting the coexistence preamble sequence in response to a determination that the threshold back-off duration has been reached. 
 
 
     
     
       12. The PLC device of  claim 11 , the program instructions further causing the PLC device to:
 transmit a data frame on the channel after transmitting the coexistence preamble sequence. 
 
     
     
       13. The PLC device of  claim 11 , wherein the threshold back-off duration is defined as a predetermined number N of coexistence Extended Interframe Spaces (cEIFS) durations for the PLC network. 
     
     
       14. A power line communication (PLC) device, comprising:
 a receiver coupled to a channel on a PLC network; 
 a processor; and 
 a memory coupled to the processor, the memory configured to store program instructions executable by the processor to cause the PLC device to:
 detect a coexistence preamble sequence followed by not detecting a native preamble from a remote PLC device on the PLC network channel; 
 determine whether a threshold back-off duration has been reached; 
 transmit a coexistence preamble sequence in response to a determination that the threshold back-off duration has been reached; 
 monitor a channel occupancy duration during which devices transmit on the PLC network channel; 
 determine when the channel occupancy duration of a given PLC technology exceeds a network duty cycle time (ndcTime); and 
 back off from the channel for a duty cycle Extended Interframe Space (dcEIFS) duration when the channel occupancy duration exceeds ndcTime. 
 
 
     
     
       15. The PLC device of  claim 14 , wherein values for the ndcTime and dcEIFS parameters are selected based upon channel access technologies used by PLC devices on the PLC network. 
     
     
       16. The PLC device of  claim 14 , wherein the threshold back-off duration is defined as a predetermined number N of coexistence Extended lnterframe Spaces (cEIFS) durations for the PLC network. 
     
     
       17. The PLC device of  claim 16 , wherein the values of ndcTime and (N×cEIFS) are chosen to given precedence to a particular approach. 
     
     
       18. The PLC device of  claim 17 , wherein ndcTime is less than N×cEIFS to give precedence to duty cycle approach. 
     
     
       19. The PLC device of  claim 17 , wherein N×cEIFS is less than ndcTime to give precedence to a long cycle approach. 
     
     
       20. The PLC device of  claim 16 , wherein the values of ndcTime and N are selected so that ndcTime is less than the value of (N×cEIFS).